Bra cup structure

ABSTRACT

The bra cup structure of the present disclosure comprises two laminated flexible layers  2, 3  enclosing between them a pouch  4  containing a malleable material made of silicone gel filled with polymer microspheres; the pouch  4  is formed by two thin polymer films  5, 6  sealed to one another, for example made of polyurethane. The inner layer  3  is made of viscoelastic foam.

The present invention concerns a bra cup structure.

There is known from the document FR 2 813 167 a bra cup structure constituted of two layers of foam stuck together enclosing between them a pouch containing a malleable material, in this instance a liquid. The foam layers may be stuck to textile layers. Moreover, the document WO 00/47068 also discloses a similar structure, improved by a new choice of malleable material for filling the pouch.

Although each of these innovations aims to create a bra having a push-up effect, for users work remains to be done in terms of improving comfort, invisibility, bulking and raising effect and freedom of movement. Such is the aim of the present invention.

To achieve it, the present invention proposes a bra cup structure including two flexible, interior and exterior, layers stuck together, enclosing between them, for example in their lower part, a pouch containing a malleable material, characterized in that the malleable material is a silicone gel charged with polymer microspheres and in that the interior layer is a visco-elastic foam layer while the exterior layer is made of flexible material chosen from non-visco-elastic foams and textile filling materials.

Textile filling materials are understood here to mean materials based on natural or synthetic fibers which are arranged to give a certain volume, a certain thickness, with a padding function, whether this be by a weaving method, a knitting method, a needling method, a felting method or some other method. This is in particular an artificial wadding such as padding fibers known under the designation Fiberfill®, a linked double-knit mesh such as 3D knitted fabrics known under the name of “spacer”.

If the external layer is made of foam, a non-visco-elastic polyurethane foam will advantageously be chosen. This is because a non-visco-elastic foam has the advantage of being able to be obtained in white, whereas visco-elastic foams have a marked tendency to yellow (on a gray scale used by the Applicant, the score of visco-elastic foams is less than 3, while a standard foam is greater than 4). Yet there is high demand for white bras, and these cannot be obtained when produced from visco-elastic foam.

The Applicant has found that this particular combination of materials, one of which does not have shape memory (the silicone gel) and the other of which, by contrast, does have shape memory (the visco-elastic foam of the interior layer), resulted in noteworthy comfort properties and in particular behavior extremely close to that of the flesh when the structure is pressed with the fingers, the exterior layer actually only being involved a little in this artificial flesh texture which is formed by the visco-elastic interior layer and the silicone gel, with a feel resembling the texture of the breast. This interior face, under the action of body heat and the pressure exerted by the breast, is distributed over the periphery of the breast, fills the gaps and creates filled areas for remodeling the breast and giving it a naturally round shape. When the exterior layer is made of standard foam, the Applicant has surprisingly found that the feel qualities on the interior side in contact with the breast are not noticeably compromised on wearing, compared with a production with a visco-elastic exterior layer, even if said feel qualities are necessarily somewhat less when touched with the fingers (finger push test). Furthermore, the use of a standard polyurethane foam on the outside makes it possible to obtain further advantages in addition to the good white color already mentioned: one of the advantages is the lightness of these foams, frequently around 30 kg/m³, whereas visco-elastic foams often have a mass per unit volume of 50 kg/m³. By replacing an exterior shell layer of visco-elastic foam of 50 kg/m³ with a foam layer of standard foam of 30 kg/m³, a bra is lightened by around 8%. This lightening very substantially contributes to wearing comfort: specifically a lower weight of the bra means that the back squeezes the user less and the straps pull less. Another advantage linked to this lightening is that the bra moves less while it is being worn; comparative tests have shown a drop in the neckline after eight hours of wearing of only 3 mm with a bra according to the invention compared with 6 mm on average when the external shell is made of visco-elastic polyurethane foam of 50 kg/m³. Such a bra therefore provides increased satisfaction for the user.

Advantageously, the malleable material is disposed in a pouch constituted by two polymer, for example polyurethane, films sealed to each other. Their thickness is advantageously very small so as not to induce any effect perceptible to the touch. The thickness is preferably less than 40 μm and more advantageously of the order of 35 μm.

The malleable material has a mass per unit volume that is advantageously between 0.60 and 0.75 g/cm³.

The pouch filled with malleable material is inserted during a molding (thermoforming) operation between the two interior and exterior layers, the interior layer being of visco-elastic foam, the mass per unit volume of which is advantageously between 30 and 65 kg/m³ and advantageously of the order of 50 kg/m³. If an ordinary polyurethane foam layer is used for the exterior face, the mass per unit volume thereof is preferably around 30 kg/m³.

The interior layer of visco-elastic foam is preferably stuck to a textile material, such as a polyester locknit fabric, before they are stuck to each other, this textile material being disposed on the outside of the cup. The exterior layer may also be stuck to a textile material, in particular in the case of a polyurethane foam. On the other hand, if a padding element such as a “spacer” is used, this already includes a textile face which can act as a visible exterior face of the cup.

The weight of silicone gel in the pouch is advantageously very low, preferably less than 10 grams, advantageously substantially between 7 and 9 grams.

The shape of the pouch is substantially elliptical, with a major axis between 8 and 15 cm and a minor axis between 4.5 and 7 cm. Its mean thickness is preferably between 2 and 3 mm.

In a particularly advantageous manner, the normalized 25% depression force in the cup of the invention, in the part in which the pouch is situated, is between approximately 2 and 3.5 N and the normalized 65% depression force at the same location is between approximately 15 and 40 N.

Although, in an advantageous embodiment which will be illustrated below, the pouch is located in the lower part of the cup and is thus involved in the “push-up” effect and support of the breasts, it is also possible to provide for the pouch to be in the upper part or in lateral zones, where, in combination with the foam layers, it provides the comfort of its particular texture.

Other features and advantages of the invention will emerge from the following description of one embodiment. The appended drawings will be referred to, representing:

in FIG. 1, a cup structure conforming to the invention seen from the front;

in FIG. 2, the section II-II of the cup structure from FIG. 1 in vertical section;

in FIGS. 3 and 4, two malleable material pouch shape variants.

After thermoforming, a thermoformed cup structure 1 has a substantially hemispherical shape, having a depth H of the order of 70 to 75 mm. It is composed of two stuck together flexible layers, an exterior layer 2 (for example made of ordinary 30 kg/m³ polyurethane foam) and an interior layer 3 (made of visco-elastic foam) respectively, which enclose between them, in their lower part, a pouch 4 of malleable material, formed by two polyurethane films 5, 6 welded at their edges. As seen in FIG. 1, the malleable material pouch 4 is substantially the shape of an almond limited by the dotted-line curve that marks the upper edge 7 of the pouch 4; the pouch 4 essentially occupies the lower part of the cup, substantially less than half of the cup and preferably less than its lower third. In section, as seen in FIG. 2, the malleable material pouch 4 has a weakly biconvex (substantially flat) overall shape tapered at the edges, the shape of the pouch being modifiable when worn in contact with the chest and by reason of movements. The greatest thickness of the cup, at the thickest location of the pouch 4, is of the order of 10 to 14 mm (pouch and foam layers). Before assembling them, the layer 2 of ordinary foam and the layer 3 of visco-elastic foam are stuck to a fine textile layer 11 and 12, for example in polyester, which facilitates holding and manipulating them and prevents problems of shrinkage of the material during molding.

In one embodiment, the malleable material is based on a two-component silicone gel of RTV2 type (cross-linked at room temperature), for example of the Silibione® type from the company Bluestar Silicones. The silicone gel has a dynamic viscosity before cross-linking that is between 6000 and 250 000 mPa·s at 25° C., for example. Its mass per unit volume before introduction of the charge is of the order of 1 to 1.5 g/cm³. A charge of polymer microspheres is mixed with the silicone gel, for example Expancel® microspheres from the company Akzo-Nobel. These expanded acrylic-based polymer microspheres, of 20 to 80 μm diameter, are mixed with the gel so that the mass per unit volume of the material after mixing is between 0.60 and 0.75 g/cm³. In one embodiment, the microspheres form from 1 to 3% by weight of the mixture.

The pouch 4 is fabricated as follows. Two thin films 5, 6 of polyurethane are assembled beforehand to form an almond-shaped envelope with heat-welded edges, for example, and having an opening through which the mixture of the two constituents of the silicone gel are poured into the envelope. The opening is closed, the whole optionally placed in a metal mold having the definitive shape of the pouch, and the whole is cross-linked by heat treatment. A pad or pouch 4 of malleable material is obtained in this way. The dimensions of the pouch depend on the size of the bra to which it is applied, but it advantageously measures between 8 and 15 cm along its major axis and between 4.5 and 7 cm along its minor axis, and its thickness, relatively uniform apart from the edges, is between 1.5 and 5 mm, preferably between 2 and 3 mm. According to the invention, the filling of the envelope is limited, preferably to less than 10 grams, so that the filled envelope is not hard but to the contrary remains flexible, pliable, and allows depression by a finger. In practice, an envelope 4 of almond or ellipse shape approximately 10.5 cm×5.5 cm with a mean thickness of 2.6 mm filled with 9 g of silicone gel has proved satisfactory. Prior to thermomolding, the thickness of the two non-compressed visco-elastic foam and non-visco-elastic foam layers is around 8 mm.

There will now be described the fabrication of the cup from layers 2, 3 of foam stuck to their textile layer 11, 12. The layers 2, 3 of foam in the non-thermoformed state have a thickness of approximately 6 mm.

For the fabrication of the cup structure 1, the first step is to thermoform the exterior layer 2, 11 of foam in a mold adapted to the shape of the cup, for example for between 1 and 2 minutes at a temperature of the order of 160 to 190° C., for example 180° C., adjusting the separation of the two parts of the mold to enable uniform compression/molding of this layer 2, 11.

In a second step that may be carried out in the same mold or in a similar mold, there are stuck together the interior layer 3, 12 of visco-elastic foam that has just been thermoformed and the exterior, non-visco-elastic layer 2, 11 which has not yet been thermoformed, for example by coating the two facing layers of foam with adhesive, advantageously a water-based adhesive. A temporary mask is placed between the two faces to be stuck together to prevent sticking at the level of the area that must later be occupied by the pouch and an adjacent area communicating with the edge of the layers. This mask may comprise a foam pad substantially occupying the area that the pouch will occupy. The spacing between the male and female parts of the mold is adjusted to enable compression of the two layers and thermoforming is effected for 40 s for example at the same temperature as previously. After this step, the two layers 2 and 3 are stuck to their interface 8, except in the area in which the pouch 4 must be inserted and in a passage enabling access to that area. The mask and the foam pad are removed. The combined thickness of the two thermoformed layers 2, 3 is between 2 and 3 mm.

In a third step, the pouch 4 and/or the area between the layers 2 and 3 of foam into which it is inserted are coated with adhesive and the pouch 4 placed in this area. The passage left open is also coated with adhesive. Fixing is assured by heat and pressure in the mold, for 40 s at 180° C. for example.

The whole can be cut to the exact shape that the cup must have, as shown in FIGS. 1 and 2.

The thermoforming mold may for example be of the type described in the document GB 1 577 099 or the document FR 2 906 111 in the name of the Applicant.

When thermoforming the structure 1, a compressed border 9 is formed in the lower half of the hemispherical cup that will enable the optional insertion of a wire and connection of the cup with the substantially plane basque of the bra (by sewing, welding or gluing) and to the upper part of the cup an upper tab 10 that will serve for the connection with the bra strap. The border 9 must be formed either as shown in the plane of the base of the cup and face outwards or to the contrary in line with the cup, depending on the making up technique envisaged.

Once the cup structure 1 has been thermoformed, it may be used in a standard bra, into which it is assembled when making up the bra. The structure is then advantageously covered on the outside by a decorative textile material, possibly lace, while the polyester interior surface 12 may serve directly as the interior textile surface of the finished bra.

The whole of the bra could be fabricated directly by thermoforming, using techniques known for multilayer bras, which principle does not lie outside the scope of the invention. In this case, the pouch 4 is disposed in locations formed between foam layers stuck to textile layers and already having substantially the shape of the finished bra (cups, separator, basque and back).

Various experiments have been conducted to determine the essential parameters that would lead to a result deemed particularly satisfactory by users. The depression force for compressions of 25% and 65% was measured on different samples using a procedure standardized by the ASTM standard D3574-95 but adapted to the subject matter of the invention, to enable tests to be carried out on the finished products (namely the bra cup). This essentially entails adapting the size of the plates of the Zwick 22.5 dynamometer test machine with a 1000 N force sensor, namely a square perforated bottom plate 150 mm×150 mm and a circular top plate of 45 mm diameter.

The samples were prepared by marking the area to be measured in the middle of the area of the pouch 4. The sample was first compressed twice to 75% of its thickness at a rate of 4 mm/s and then left to rest for 6 minutes. The indentation force deflection (IFD) compression resistance at 25% and 65% were measured by compressing the sample at a rate of 0.85 mm/s to 25% and then 65% of its thickness, the force being measured after a resting time of 60 s.

The results of 24 measurements are set out in the appended table in which bold type is used for the tests carried out on cups prepared by juxtaposing an interior layer of visco-elastic foam and a pouch of silicone gel in accordance with the invention, with diverse variations as to the nature of the silicone gel, its weight and the thickness of the polyurethane film or of the exterior layer. The foam was unchanged in these samples, having a density of 50 kg/m³. Although the bras of the present invention comprise an exterior layer or shell made of non-visco-elastic foam, it is clear that the wearing feel qualities were not substantially modified by replacing the visco-elastic shell layer with a non-visco-elastic layer, indicating that the essence of the wearing feel qualities originates from the combination of the two internal layers of the bra (visco-elastic foam and silicone gel), forming the artificial flesh. The other tests were carried out on commercially available cups with different structures deemed already to provide comfort and chest support.

These results were compared to touch and wear tests which showed that the structures comprising the interior layer combining the visco-elastic foam and the pouch of silicone gel were perceived much more favorably than the others, except for sample 22, deemed too hard, probably because of an excessive combination of silicone pouch weight and thickness of and polyurethane film thickness, and to a lesser degree sample 19, also with a polyurethane film thickness of 40 μm. In particular, sample 24, the exterior layer of which is made of non-visco-elastic polyurethane foam, was deemed satisfactory. In the final analysis, it is apparent that the satisfactory samples conforming to the invention had the remarkable property of a 25% IFD measurement substantially between 2 and 3.5 N and a 65% IFD measurement substantially between 15 and 40 N for cups of medium size. This combination yields a softness deemed remarkable to touch and to wear, and enables a cup to be obtained of high adaptation power, adjusting perfectly to the shape and the particular size of the breast to bring about a round and raised chest. This comfort lasts throughout a day of wear and allows great freedom of movement: the silicone pouch can deform and adapt to the chest in movement, permanently filling hollow spaces.

The measurements reported above were effected on cups of medium size (90B in France/75B in Europe). For cups of different size, the shape of the pouch, the dimensions and the weight in particular may differ, which may impact on the measured values. FIG. 3 represents a pouch 4 adapted to a cup of small size (70A in Europe), of more compact shape with an extremity truncated compared to the basic shape, from approximately 90 mm to 47 mm. FIG. 4 represents a pouch 4 adapted to a cup of larger size (80D in Europe), of more elongate shape compared to the basic shape, approximately 120 mm by 30 mm.

COMPARATIVE TABLE Sample IFD25% (N) IFD65% (N) Comments 1 1.71 7.34 Foam shell 2 1.72 7.61 Silicone gel pad 3 2.26 10.52 Foam shell 4 3.25 12.72 Foam shell 5 1.25 13.31 Foam shell 6 2.06 15.49 Inv gel-1/9 g/film 35 μm 7 2.28 15.62 Inv gel-0/20 g/film <35 μm 8 3.37 17.17 Foam and air pad 9 4.27 17.62 Foam shell 10 2.25 18.17 Inv gel-1/9 g/film 35 μm 11 2.32 19.01 Inv gel-2/5 g/film 40 μm 12 4.09 20.48 Fiber shell 13 2.41 20.6 Inv gel-1/9 g/film 35 μm 14 2.2 21.75 Inv gel-1/7 g/film 35 μm 15 2.26 23.45 Inv gel-2/5 g/film 35 μm 16 2.48 26 Inv gel-2/5 g/film 40 μm 17 2.3 30.85 Inv gel-2/7 g/film 35 μm 18 6.11 31.74 Foam shell 19 2.79 39.12 Inv gel-2/5 g/film 40 μm 20 5.11 45.32 Foam and air pad 21 7.53 72.38 Foam shell 22 4.71 89.47 Inv gel-2/10 g/film 40 μm 23 3.64 102.29 Foam and air pad 24 3.29 35.98 Inv gel-1/9 g/film 35 μm + non-visco-elastic polyurethane foam 

1. A bra cup structure including two flexible, interior and exterior, layers stuck together, enclosing between them a pouch containing a malleable material, characterized in that the malleable material is a silicone gel charged with polymer microspheres and in that the interior layer is a visco-elastic foam layer while the exterior layer is made of flexible material chosen from non-visco-elastic foams and textile filling materials.
 2. The structure as claimed in claim 1, wherein the malleable material is disposed in a pouch constituted by two polymer, for example polyurethane, films sealed to each other.
 3. The structure as claimed in claim 2, wherein the thickness of the films is less than 40 μm.
 4. The structure as claimed in claim 1, wherein the malleable material of the pouch has a mass per unit volume between 0.60 and 0.75 g/cm³.
 5. The structure as claimed in claim 1, wherein at least the interior layer of visco-elastic foam is stuck to a textile material.
 6. The structure as claimed in claim 1, wherein the weight of silicone gel in the pouch is substantially between 7 and 9 grams.
 7. The structure as claimed in claim 1, wherein the shape of the pouch is substantially elliptical, with a major axis between 8 and 15 cm and a minor axis between 4.5 and 7 cm.
 8. The structure as claimed in claim 1, wherein the mean thickness of the pouch is between 2 and 3 mm.
 9. The structure as claimed in claim 1, wherein in the cup of the invention, in the part in which the pouch is situated, the normalized 25% depression force is between approximately 2 and 3.5 N and the normalized 65% depression force at the same location is between approximately 15 and 40 N. 